I would first like to say I have done numerous Google and Bing searches in this issue and I am a big overwhelmed.

This is the main issue. I had Ubuntu on my Toshiba Satellite laptop and I wanted to switch to Debian. I know I could easily have configured my laptop to do a CSM boot and all would be good, but I wanted UEFI setup purely for obsessive compulsive reasons.

I booted Ubuntu from a USB drive and dismounted the swap partition, I then used the Disks app to completely erase and overwrite my 2TB drive. About 14 hours later I decided to install Debian off my DVD drive. In my laptop setup, I had secure boot disabled, cleared the secure boot keys just in case, and found no setting for a Windows Fast Boot to disable. The DVD booted in UEFI mode and completed the install. When trying to boot off the hard drive I received an invalid boot media error.

On my other laptop, I downloaded the rEFInd boot manager app and installed it on a USB stick. On the first laptop, I booted the Ubuntu Live USB stick and downloaded the rEFInd boot manager and installed to /dev/sda1 (my EFI boot partition). The laptop still had an invalid boot media error. I inserted the rEFInd USB drive I created earlier and it booted off that and found the Debian install and previously installed rEFInd boot loader. I chose to boot Debian and the Grub menu showed up and then continued to load correctly. My laptop would boot with the USB drive installed, but not off the hard drive. I found this unacceptable. Now to the acceptable solution.

I found my old Windows 8 install DVDs and proceeded to reset my laptop to factory (Windows) defaults. After the install, Windows booted in EFI mode!

I shrunk the main Windows partition to install Debian. After asking Windows permission to allow me to boot from DVD, the Debian install went off without a problem. When I removed all removable media, the Grub bootloader actually showed up and now I have a fully functional Debian UEFI system infected by Windows. My laptop had a Windows based Toshiba update app that found a firmware update, and flashed it before I installed Debian, and this may have been an issue, but Windows did boot UEFI and Debian did not. I would like to have a pure Debian UEFI install, but do not know if it will now work. Hard drive space is not an issue, and this is a hobby laptop. I was just wondering if anyone had similar issues and a possible easier fix.

I did have a similar issue when I wiped my hdd to do the same as you, I managed to overcome this by re-installing Windows 10 and then once completed I installed Debian and then wiped the windows partition, removed the extra hidden partitions (manufacturers images etc) and just left the efi boot partition and debian. After a little tweaking from a live-cd (re-sizing and moving debian partition) I just removed windows efi boot information from the efi boot partition and everything was how I wanted it. It took quite some time to get everything set up how I wanted it (spread over two days) but the results were good.

Thank you. I'm glad it wasn't just me. My EFI partition is not at the beginning, one of the recovery partitions is. After deleting that partition, can I move the EFI partition or just accept this space as lost?

I'm not at that machine right now, but from memory there was a small recovery partition that Ms created but it was only very small and I left it as I was unsure about moving boot partition, although I would not think it would be a problem but I spent too much time setting up and didn't want to break it again so opted for caution and left it.